The file of this patent application includes duplicate copies of a compact disc with a file entitled xe2x80x9c338995 code.txtxe2x80x9d, created on Jun. 11, 2001, and having a size of 92,072 bytes (92,160 bytes on disc), which is hereby incorporated by reference.
The present invention relates to signal processing, and more particularly relates to the processing of video and audio signals to embed auxiliary data (e.g. identification or control data therein), and the subsequent extraction and use of such data.
The copying and redistribution of commercial imagery and video productions has long been a cause of lost revenues to the creators/producers of such material. The advance of technology has not only expanded the means of legitimate distribution for visual/video works, but has also made it easier to copy these materials for unauthorized purposes.
Various methods have been developed to eliminate or limit both sophisticated and unsophisticated illegitimate distribution. Some of these methods rely on physical means. Others employ a xe2x80x9cdon""t copyxe2x80x9d signal to disable a machine""s recording function.
In accordance with preferred embodiments of the present invention, a multi-bit control message (sometimes termed a xe2x80x9cdigital watermarkxe2x80x9d) is embedded directly into the brightness levels of the visible portion of a video signal, or the brightness levels of a still image. Hardware or software systems can then read this control message and, for example, disable recording functions if so instructed.
Key practical issues are addressed whereby the perceptual impact of this added message can be adjustedxe2x80x94both overall and as a function of the underlying visual content. For example, a blank video sequence ought in general to have minimal visible effects, whereas active motion scenes with various areas of high detail can generally tolerate more visual energy in a watermark.
Methods are further detailed whereby the embedded message can survive lossy compression processes. An example of a lossy compression process is the MPEG video compression standard. (MPEG is commonly employed when video is distributed in digital form, e.g. on optically encoded disks.)
The sample principles are also applicable to audio.
FIG. 1 is a simple and classic depiction of a one dimensional digital signal which is discretized in both axes.
FIG. 2 is a general overview, with detailed description of steps, of the process of embedding an xe2x80x9cimperceptiblexe2x80x9d identification signal onto another signal.
FIG. 3 is a step-wise description of how a suspected copy of an original is identified.
FIG. 4 is a schematic view of an apparatus for pre-exposing film with identification information in accordance with another embodiment of the present invention.
FIG. 5 is a diagram of a xe2x80x9cblack boxxe2x80x9d embodiment of the present invention.
FIG. 6 is a schematic block diagram of the embodiment of FIG. 5.
FIG. 7 shows a variant of the FIG. 6 embodiment adapted to encode successive sets of input data with different code words but with the same noise data.
FIG. 8 shows a variant of the FIG. 6 embodiment adapted to encode each frame of a videotaped production with a unique code number.
FIGS. 9A-9C are representations of an industry standard noise second that can be used in one embodiment of the present invention.
FIG. 10 shows an integrated circuit used in detecting standard noise codes.
FIG. 11 shows a process flow for detecting a standard noise code that can be used in the FIG. 10 embodiment.
FIG. 12 is an embodiment employing a plurality of detectors in accordance with another embodiment of the present invention.
FIG. 13 shows an embodiment of the present invention in which a pseudo-random noise frame is generated from an image.
FIG. 14 illustrates how statistics of a signal can be used in aid of decoding.
FIG. 15 shows how a signature signal can be preprocessed to increase its robustness in view of anticipated distortion, e.g. MPEG.
FIGS. 16 and 17 show embodiments of the invention in which information about a file is detailed both in a header, and in the file itself.
FIGS. 18-20 show details relating to embodiments of the present invention using rotationally symmetric patterns.
FIG. 21 shows how the invention can be practiced by encoding xe2x80x9cbumpsxe2x80x9d rather than pixels.
FIGS. 22-26 detail aspects of a security card according to one embodiment of the present invention.
FIG. 27 is a flow chart showing an illustrative method in which both local and global scaling are employed in encoding a motion picture signal, so that the embedded control signal can be detected (and used to control associated equipment) notwithstanding lossy compression/decompression of the encoded motion picture signal.